1. Field of the Invention
The present invention relates to a cooling structure in a compressor in which a compression member delimiting a compression chamber is moved according to the rotation of a rotary shaft so that a refrigerant is sucked from a suction chamber into the compression chamber, by the motion of the compression member, and discharged from the compression chamber, and a shaft seal means is arranged between the housing of the compressor and the rotary shaft so as to seal the inside of the housing of the compressor.
2. Description of the Related Art
In the compressor disclosed in Japanese Unexamined Patent Publication No. 10-26092, in order to lubricate the shaft seal means arranged between the housing and the rotary shaft, a communication port is branched from the intermediate portion of the suction refrigerant passage and connected to the shaft seal means. A portion of the refrigerant flowing in the suction refrigerant passage arrives at the shaft seal means via the communication port, so that the lubricant flowing together with the refrigerant lubricates the shaft seal means.
In the compressor disclosed in Japanese Unexamined Patent Publication No. 11-241681, there is provided a decompression passage in the rotary shaft, which reaches the shaft seal means, and the decompression passage is decompressed by the sucking action of a fan rotating integrally with the rotary shaft. The region in which the shaft seal means is arranged is connected to the control pressure chamber in which the swash plate is accommodated. The refrigerant flows from the control pressure chamber into the region of the shaft seal means by decompression in the decompression passage. Therefore, the lubricant flowing together with the refrigerant lubricates the shaft seal means.
The sealing function of the shaft seal means early deteriorates in a high temperature environment. Therefore, it is important not only to lubricate but also to cool the seal means. In the compressor disclosed in Japanese Unexamined Patent Publication No. 10-26092, the communication port reaches the region in which the shaft seal means is arranged. Therefore, lubricant that has flowed into the communication port does not flow smoothly. When lubricant does not flow smoothly, the shaft seal means can not be efficiently cooled.
In the compressor disclosed in Japanese Unexamined Patent Publication No. 11-241681, the refrigerant that flows from the control pressure chamber into the region in which the shaft seal means is arranged is returned into the control pressure chamber via the decompression passage in the rotary shaft. Therefore, lubricant flows smoothly in the region in which the shaft seal means is arranged. However, the temperature in the control pressure chamber is high, and the temperature of the lubricant that flows into the region in which the shaft seal is arranged is also high. Therefore, although it is necessary to provide a decompression means (for example, a fan mechanism) for generating a pressure difference between the region in which the shaft seal means is arranged and the control pressure chamber, the shaft seal means cannot be effectively cooled.
It is an object of the present invention to effectively cool a shaft seal device arranged between a housing and a rotary shaft for sealing the inside of the housing of the compressor.
In order to accomplish the above object, the present invention provides a compressor comprising a housing having a suction chamber, a discharge chamber and at least one compression chamber, at least one compression member delimiting the at least one compression chamber, a rotary shaft supported by the housing to move the compression member so that a refrigerant is sucked from the suction chamber into the compression chamber and discharged from the compression chamber into the discharge chamber and a shaft seal device arranged between the housing and the rotary shaft to seal the inside of the housing of the compressor, an accommodation space accommodating the shaft seal device, and a passage connected to the accommodation space to allow the refrigerant to come into contact with the shaft seal device, wherein the passage forms a passageway from a suction pressure region outside the housing to the suction chamber via the accommodation space, and an inlet from a portion of the passage arranged on the upstream side of the accommodation space to the accommodation space and an outlet from the accommodation space to a portion of the passage arranged on the downstream side of the accommodation space are arranged separately from each other.
The refrigerant flowing from the suction pressure region located outside the entire housing flows from the passage portion on the upstream side into the accommodation space via the inlet and flows out from the accommodation space into the passage portion on the downstream side via the outlet. In the accommodation space, the inlet and the outlet are separately arranged from each other, and therefore, the lubricant smoothly flows in the accommodation space. Further, the temperature of the refrigerant in the suction pressure region outside the housing of the compressor is low, and the temperature of the lubricant flowing together with the refrigerant of low temperature is also low. Accordingly, the shaft seal device accommodated in the accommodation chamber can be effectively cooled.
Preferably, the inlet is located above the rotary shaft, and the outlet is located below the rotary shaft.
A portion of the lubricant, which flows from the inlet into the accommodation space, flows downward along the shaft seal device and cools the shaft seal device. The lubricant, which has cooled the shaft seal device while it is flowing downward along the shaft seal means, flows out from the outlet. The inlet is arranged above the rotary shaft and the outlet is arranged below the rotary shaft, and therefore, the lubricant smoothly flows along the shaft seal device.
Preferably, the rotary shaft extends through the front housing composing the housing of the compressor and protrudes outside the housing, the shaft seal device is arranged between the rotary shaft and the front housing, the passage extends in the wall of the front housing and is connected to the accommodation space, and the inlet of the passage in the entire housing is arranged in the front housing.
The length of the passage from the outside of the housing to the accommodation space is short, and therefore, an increase in the temperature of the refrigerant can be suppressed while the refrigerant flows from the outside of the housing into the accommodation space.
Preferably, the compressor is a variable displacement piston type compressor comprising said housing including a front housing and a cylinder coupled to the front housing and having a plurality of cylinder bores around the rotary shaft, pistons accommodated in the cylinder bores as the compression members to delimit the compression chambers, a tiltable swash plate arranged in a control chamber in the front housing and rotated by the rotary shaft, so that a tilt angle of the swash plate is changed by adjusting a pressure in the control pressure space, the accommodation chamber and the suction chamber being separated from each other by the control pressure chamber, and the cylinder, and a second shaft seal device to shut off the communication between the accommodation space and the control pressure chamber along the circumferential surface of the rotary shaft.
The present invention is preferably applied to a variable displacement piston type compressor in which the accommodation space and the suction chamber are separated from each other so that the control pressure chamber and the cylinder can be interposed between them.
Preferably, the shaft seal device comprises a mechanical seal. The mechanical seal is excellent in the pressure-resistance property.
Preferably, the shaft seal device comprises a lip type seal. When the lip seal is used, the shaft sealing structure can be composed at low cost and further it is possible to provide an excellent oil-seal property by the lip seal.